There is a substrate processing apparatus, which includes a placing section on which a plurality of substrate containers called cassettes, carriers or FOUPs can be placed, and which includes a plurality of processing units of a single-wafer processing type that perform parallel processing of the substrates removed from the substrate containers placed on the placing section. Transfer of the substrates from the substrate containers to the processing units is carried out by a transfer system including one or more transfer mechanisms.
In such a substrate processing apparatus including the plurality of processing units, the substrate transfer schedule during normal operation is set such that the substrates are sequentially transferred to a vacant processing unit (no substrate is loaded therein).
In the substrate processing apparatus of the aforementioned type, various situations may arise. For example, one or more processing units malfunction. In this case, the transfer schedule is changed such that lowering of throughput of the substrate processing apparatus can be restrained as much as possible. For example, Japanese patent laid-open publication JPH11-016983A describes a substrate processing apparatus including a plurality of processing units that perform the same process to substrates in parallel. If any one of the processing units malfunctions, the substrates which were scheduled to be transferred to the malfunctioning processing unit are transferred to the other functioning processing units and are processed therein.
In a substrate processing apparatus including a plurality of processing units that perform the same process to substrates in parallel during normal operation, sequential processing of product substrates is sometimes interrupted for processing of a monitor substrate. The monitor substrate is a substrate to be subjected to a new processing condition on a trial basis, for example. In this case, one or more processing units, which is selected from the plurality of processing units that process the product substrates during the normal operation, is assigned to the processing of the monitor substrate. Namely, the operation mode of the selected processing unit is set in a monitoring mode. The operation mode of the non-selected processing units is maintained in a normal mode for processing of product substrates. Then, the monitor substrates are exclusively loaded into the processing units set in the monitoring mode, into which unit the loading of the product substrates are prohibited. The processing of the product substrates are performed only in the processing units maintained in the normal mode. However, in such an operation, the throughput of the substrate processing apparatus for the product substrates is lowered.